f = oda ~ oda_lag + p_polity2 + gdppc + pop + factor(year)*factor(agency) + trade + alliance + infant_mortality
f1 = update(f, '.~.+alliance:independence')
f2 = update(f, '.~.+trade:independence')
f3 = update(f, '.~.+infant_mortality:independence')

mod1 = lm(f1, dat)
mod2 = lm(f2, dat)
mod3 = lm(f3, dat)

all_motives = list(mod1, mod2, mod3)
se = lapply(all_motives, function(i) sqrt(diag(sandwich(i))))

print(screenreg(all_motives, omit.coef='factor', digits=3, override.se=se))
